Neutrino transport in stellar collapse

Abstract

A multigroup flux-limited diffusion approximation to the equations of neutrino transport is outlined. Because the approximation requires no assumptions about the functional form of the neutrino distribution, it enables detailed tracing of the evolution of neutrinos when applied, as it is here, as part of a description of a collapsing stellar core. Presented are some results of such collapse calculations made using this method. They show that during the crucial period of lepton loss from the system, the neutrinos are not accurately modelled by a thermal distribution.